WO2014006543A1

WO2014006543A1 - Infrared beacon and configuration system for configuring same

Info

Publication number: WO2014006543A1
Application number: PCT/IB2013/055247
Authority: WO
Inventors: Ingrid Christina Maria Flinsenberg; Roel Peter Geert Cuppen; Elke Marieke Lambert DAEMEN; Evert Jan Van Loenen; Rosemarie Jolanda Elise RAJAE-JOORDENS
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-07-02
Filing date: 2013-06-26
Publication date: 2014-01-09

Abstract

An infrared beacon 100 is provided which may be used in a localization system. The infrared beacon comprises an infrared emitter 110 for emitting infrared light, a light sensor 120 for measuring the amount of ambient light outside the infrared beacon,and a controller 130 for regulating the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon the measured amount of ambient light. By changing the infrared visibility in dependence upon the ambient light, the beacon has a more constant infrared visibility. Thus more detailed localization, less dependent upon ambient light levels, is possible.

Description

INFRARED BEACON AND CONFIGURATION SYSTEM FOR CONFIGURING SAME

FIELD OF THE INVENTION

The invention relates to an infrared beacon comprising an infrared emitter for emitting infrared light. The invention further relates to a configuration system for configuring an infrared beacon.

BACKGROUND OF THE INVENTION

For many applications there is a need to detect the locations of people. One such application is hospitals in which it is advantageous to know the location of staff and/or patients and/or visitors in the hospital. For example, localization knowledge may be used an input for a planning system, assigning personnel to medical alerts on the basis of proximity. Another application is to update the ambient atmosphere of a patient room, or part thereof.

Such ambient atmospheres may be created in patient rooms in a hospital in order to create a relaxing atmosphere. Such ambient atmospheres can be created by ambient systems capable of creating a special lighting of the room, presenting relaxing video or images or for example sounds or music. A relaxing atmosphere is important for the patient's well-being and may contribute to the healing process for the patient.

However, whereas an optimal ambient atmosphere may be created for optimizing the patient's well-being, this atmosphere may not be suitable in certain contexts, e.g., where a doctor visits the patient, when cleaning personnel has to clean the room or when family visits the patient.

To accurately describe the context, accurate localization of the people in the hospital is needed. Differentiating between a doctor being in a (multi) patient room, and a doctor standing next to a particular bed in that patient room, enables more accurate context descriptions, thereby enabling better, additional and more meaningful solutions.

SUMMARY OF THE INVENTION

One way to determine the location and identity of people involves the use of infrared light. An infrared beacon may be placed in an area where localization is desired. An infrared detector worn by a person may detect the infrared beacon, thus also detecting presence in the area. The badge may respond by sending an ID, e.g., using RF or the like. It is found that IR beacons lack the desired accuracy to allow localization at a level more detailed than room level. It is desired to have IR beacons that have a more predictable infrared visibility. Such an IR beacon may be restricted to a particular area, e.g., around a particular bed.

It would advantageous to have an improved infrared beacon. The infrared beacon comprises an infrared emitter for emitting infrared light, a light sensor for measuring the amount of ambient light outside the infrared beacon, and a controller for regulating the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon the measured amount of ambient light. In an embodiment the controller is configured to increase infrared visibility if the measured amount of ambient light increases over a first level, and wherein controller is configured to decrease the infrared visibility if the measured amount of ambient light decreases below a second level.

The infrared visibility of an infrared beacon is very sensitive to and dependent on the amount of visible light present in the area. During the night when detection of the IR is not impeded by visual light, visibility is high. But during the days, especially if sunny, the IR detection can be severely influenced. Of course, at room level, localization is not a problem due to the physical restrictions coming to play. In this case, the intensity of the infrared light of the beacons may set to its maximum level since walls block all infrared light to other rooms. For more detailed localization this is a problem however. Depending on the visible light conditions, the localization accuracy can differ several meters making the use of accurate contexts impossible. Boosting these beacons will only extend their range, making their accuracy even worse.

Since the infrared beacon comprises a light sensor for measuring the amount of ambient light outside the infrared beacon the infrared visibility may be regulated in dependence upon the measured amount of ambient light. Thus when IR visibility is problematic, e.g., if ambient light is high, the visibility is improved. When IR visibility is not problematic, visibility is reduced. The influence of lighting conditions on the area in which the IR emitter is visible from an infrared detector is reduced or eliminated. Thus the accuracy of localization is improved. The light sensor may be a visible light sensor.

The infrared beacon may be used together with ambient systems to better adapt the ambient atmosphere in a room or other environment in dependence of a person in a room, or a particular area of the room.

In embodiments, infrared visibility is regulated by increasing or decreasing the amount of infrared light emitted by the emitter. In embodiments, the infrared visibility is regulated by changing the field of view of the emitter, e.g., through a field of use mechanism, such as a cone or a lens.

The relation between measured ambient light and the settings of the beacon may be stored in various ways, e.g., as a formula, which may be evaluated by a processor or DSP, e.g., of the beacon, or as a look-up table. The infrared beacon may be restricted to a particular area, e.g., around a particular bed by limiting its infrared visibility to the particular area. The infrared visibility remains approximately equal during differing lighting conditions.

A further aspect of the invention concerns a configuration system for configuring an infrared beacon. The system comprises a mobile infrared detector, for determining the infrared visibility of infrared beacon from a current location of the infrared detector, a first interface for receiving an indication from a user indicating if the current location of the infrared detector is inside or outside a desired field of view, a second interface with a controller of the infrared beacon for regulating the infrared visibility of the infrared beacon to at least two different states, and a memory for storing the indication and the infrared visibility of the infrared emitter from the current location of the infrared detector as determined by the infrared detector for each of the at least two different states. The area in which an IR beacon is visible may thus be adapted to a desired field of view. Moreover, the area may be changed during use, for example to adjust for a changed desired field of view or an aging IR emitter.

For each amount of ambient light a setting can be found that gives an infrared visibility that matches best the desired infrared visibility, by measuring the actual infrared visibility and comparing it to a desired infrared visibility for multiple locations and multiple amounts the ambient light.

A further aspect of the invention concerns a localization system. The localization system comprises an infrared beacon and a locator device. The infrared beacon is configured to encode a digital beacon identifier in the emitted infrared light. Preferably, the localization system is unique for the infrared beacon. The locator device comprises an infrared detector for detecting the emitted infrared light and obtaining the beacon identifier from the detected emitted infrared light, and a transmitter for transmitting the beacon identifier and a digital user identifier. For example, the transmitter may be an RF transmitter. The RF transmitter may transmit to a localization server, which may use the localization information. For example, the locator device may be wearable, e.g., as a badge. The user identifier may be unique for the user. The user identifier may identify its role, e.g., a doctor identifier and a nurse identifier. If localization information is only needed locally, e.g., for navigation, the transmitter may be omitted.

The system can be used in medical environments such as hospitals, nursing homes, rehab centers, clinics, dentists, etc., as well as all other environments that require accurate IR based localization and are subject to changing visible lighting conditions over time.

The infrared beacon provides more consistent localization accuracy which is less dependent on the visible light conditions. In an embodiment, the localization system uses a light-level sensor to measure the visible lighting conditions, and adapts the emitted infrared light accordingly to achieve consistent localization accuracy independent of the visible light conditions. The infrared beacon may be used in a localization system that is able to determine the location of persons, e.g., in a hospital by using an IR based solution. In order to achieve more detailed localization, the beacon's field of view may be restricted to a particular area, e.g., around a particular bed. The infrared visibility of an infrared beacon is sensitive to, and dependent on, the amount of visible light present in the area. The light level measurements and adaptation of the IR beacon settings may be done may be done in real-time. Both the power of the emitter and the field of view of the beacon may be adapted.

The infrared beacon is an electronic device and may comprise an attaching mechanism, for attaching the beacon to a surface, e.g., a wall, a ceiling or the like. The attaching mechanism may be a surface provided with glue, etc.

A method according to the invention may be implemented on a computer as a computer implemented method, or in dedicated hardware, or in a combination of both. Executable code for a method according to the invention may be stored on a computer program product. Examples of computer program products include memory devices, optical storage devices, integrated circuits, servers, online software, etc. Preferably, the computer program product comprises non-transitory program code means stored on a computer readable medium for performing a method according to the invention when said program product is executed on a computer.

In a preferred embodiment, the computer program comprises computer program code means adapted to perform all the steps of a method according to the invention when the computer program is run on a computer. Preferably, the computer program is embodied on a computer readable medium.

An infrared beacon is provided which may be used in a localization system. The infrared beacon comprises an infrared emitter for emitting infrared light, a light sensor for measuring the amount of ambient light outside the infrared beacon, and a controller for regulating the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon the measured amount of ambient light. By changing the infrared visibility in dependence upon the ambient light, the beacon has a more constant infrared visibility. Thus more detailed localization, less dependent upon ambient light levels, is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. In the drawings,

Figure 1 illustrates as a schematic block diagram an infrared beacon,

Figure 2 illustrates as a schematic block diagram a badge, Figure 3 illustrates a room configured with a localization system, Figure 4a and 4b illustrate a relationship between ambient light and visibility,

Figure 5 illustrates as a schematic block diagram a configuration system, Figure 6 illustrates a room during configuration,

Figure 7 shows a flowchart illustrating a method of controlling an infrared beacon, Figure 8 shows a flowchart illustrating a method of configuring an infrared beacon.

It should be noted that items which have the same reference numbers in different Figures, have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item has been explained, there is no necessity for repeated explanation thereof in the detailed description.

List of Reference Numerals:

100 an infrared beacon

1 10 an infrared emitter

120 a light sensor

130 a controller

140 a memory

150 a field of view mechanism

200 a badge

210 an infrared detector

220 an RF transmitter

300 a room

310 an RF receiver

320,330 an infrared beacon

325,335 a hospital bed

300 a room

402,404 a relationship between ambient light and regulated infrared visibility

420 an amount of ambient light axis

430 an infrared visibility axis

442 a first level

444 a second level

446 a first and second level

500 a configuration system

510 an infrared detector

520 an interface for receiving an indication from a user

530 an interface with a controller of an infrared beacon 540 a memory

600 a room

620, 630 an infrared beacon

631-634 a location

640 a desired field of view

DETAILED EMBODIMENTS

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more specific embodiments, with the understanding that the present disclosure is to be considered as exemplary of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described.

Figure 1 illustrates as a schematic block diagram an infrared beacon 100. Beacon 100 comprises an infrared emitter 1 10. Infrared emitter 1 10 emits an infrared light. In a more advanced embodiment emitter 1 10 emits a recognizable light pattern, e.g., a pattern of turning the emitter on and off. Emitter 1 10 is arranged in beacon 100 so that the infrared light emitted by emitter 1 10 may be detected outside beacon 100. The use of recognizable light patterns is known, per se, e.g., from IR remote controllers. The beacon may encode a beacon identifier in the emitted IR light. The beacon identifier may be obtained from the emitted IR light with IR detector. The beacon identifier is preferably unique for the beacon, at least within the area in which the localization system is used.

Beacon 100 further comprises a light sensor 120. Light sensor 120 is arranged to measure the amount of light at the outside of the beacon. Typically, light sensor 120 is configured to sense visible light. The ambient visible light in the room is known to interfere with the detection of infrared light. Various choices may be made about the exact nature of light sensor 120, e.g., the precise spectrum of light measured, or the unit in which the amount is reported. Light sensor 120 is preferably not or less sensitive to the infrared light of emitter 1 10.

Beacon 100 further comprises a field of view mechanism 150 for mechanically controlling the field of view from the infrared emitter towards the outside of the infrared beacon. By controlling this field of view from the infrared emitter, it may be controlled from which locations the infrared emitter is visible. The field of view mechanism 150 controls infrared visibility of the emitter by controller along which lines of sight the emitter is visible or reducing the amount of light allowed outside the beacon.

Various field of view mechanisms, which are known per se, may be used in beacon 100. For example, field of view mechanism 150 may comprise a cone having a controllable base and arranged with the infrared emitter at the apex of the cone. By opening the base the emitter is visible from more locations; by partially closing the base the emitter is visible from fewer locations. The inside of the cone may be coated with an infrared-absorbing coating. For example, field of view mechanism 150 may comprise a controllable aperture, e.g., an adjustable diaphragm. The diaphragm may be a disk having a variable opening. The diaphragm is used to restrict the amount of infrared light emitted out of the beacon. The field of view mechanism 150 may also comprise one or more lenses. The lenses are arranged to control the field of view of the infrared emitter in an adjustable manner.

Beacon 100 comprises a controller 130. Controller 130 is configured to regulate the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon the measured amount of ambient light. If ambient light levels are high detection of infrared light becomes harder. However, increasing the amount of infrared light emitted decreases accuracy of localization, i.e., the infrared emitter is visible from farther away. The controller configures the beacon to a high level of infrared visibility if detection conditions are poor, i.e., if visible light levels are high. The controller configures the beacon to a low level of infrared visibility if detection conditions are good, i.e., if visible light levels are low. In this manner both accuracy and visibility of the beacon is improved.

Infrared visibility may be regulated in at least two ways. First, the controller may be configured to regulate the amount of infrared light emitted by the infrared emitter to regulate the infrared visibility. For example, the voltage across the infrared emitter may be controlled between a low voltage value and a high voltage value. The low voltage corresponds to a level at which the infrared emitter just emits infrared light. The high voltage corresponds to a level at which the infrared emitter emits a maximum amount of infrared light, but below a breaking voltage. Second, the controller may be configured to regulate the field of view mechanism to regulate the infrared visibility. Infrared visibility may be increased by enlarging the field of view using the field of view mechanism; Infrared visibility may be decreased by reducing the field of view using the field of view mechanism.

Figure 100 further shows a memory 140. As shown, memory 140 is included in a different device than beacon 100, e.g., in a central server. However, memory 140 may also be integrated with beacon 100, this will make beacon 100 more self contained.

The controller may use various ways to regulate the infrared visibility in dependence upon measured ambient light. For example, infrared visibility may be increased if the measured amount of ambient light increases over a first level and decreased if the infrared visibility of the measured amount of ambient light decreases below a second level. The first and second level may be stored in memory 140.

Figure 4a and 4b illustrate two possible relationships, 402 and 404 between ambient light and infrared visibility. The graphs have an axis 420 showing the amount of ambient light and an axis 430 showing infrared visibility, e.g., axis 430 may represent the amount of power of the light emitter, and indirectly the amount of light generated by the light emitter. In this example, the light emitted is graphed, but the same type of relationships may be used for a field of view mechanism. Relationship 402 has a first level 442 and a second level 444. In figure 4a the first level is less than the second level. If ambient light is low, e.g., below first level 442, the infrared emitter is configured by the controller to a low level of infrared visibility, i.e., a low level of light emittance. For example, an ambient light level below 442 may correspond to darkness. If the ambient light level is very high, i.e., above the second level 444, the infrared emitter is configured by the controller to a high level of infrared visibility, i.e., a high level of light emittance. If the amount of ambient light is in between the first and second level, the infrared emitter is configured to a corresponding interpolated state. In figure 4b the first and second level coincide. Relationship 404 shows a single level 446.

Other ways of controlling the infrared visibility are possible, some which are discussed below.

Typically, the device 100 and in particular controller 130 comprises a microprocessor (not shown) which executes appropriate software stored at device 100. The software may have been downloaded and stored in a corresponding memory, e.g., RAM (not shown), of beacon 100.

One particular way of using beacon 100 is illustrated with reference to figures 2 and 3. Figure 2 shows a wearable badge 200 comprising an infrared detector 210 configured to detect the infrared emitter of beacon 100 and an RF transmitter 220. Moreover, if beacon 100 is configured to emit light in a particular pattern, e.g., to indicate its location, e.g., in the form of a number unique for the beacon, then preferably a badge is used which is configured to detect the pattern, e.g., the identification number.

Figure 3 illustrates a room 300 configured with a localization system. Room 300 comprises an RF receiver 310 and one or more an infrared beacon, shown are two beacons: infrared beacon 320 and infrared beacon 330. Beacon 320 is arranged near a hospital bed 325. Beacon 330 is arranged near another hospital bed 335. For example, an infrared beacon may be attached to a ceiling, to a bed post, and the like. Beacon 320 and 330 may be constructed as beacon 100.

During operation a user, e.g., a doctor a nurse or the like, enters room 300 wearing a badge 200. As the user approaches bed 325, the infrared detector 210 detects the beacon 320. The badge may obtain the beacon ID from the detected IR light. The badge then sends a message using RF transmitter 220 to the RF receiver 310. For example, the message may include an ID of the user and an ID of the detected beacon 320. If the user nears bed 335, the infrared detector 210 detects the beacon 330. From the messages received by receiver 310, the localization system can derive which user is localized near what bed. A room may have fewer beacons, e.g., one, or more.

If it is dark in room 300, the beacon 320 and 330 are easy to detect. If the beacons were not controlled, their infrared emitters would be visible across the room. To counter this, the controllers of beacons 320 and 330 reduce the amount of emitted infrared light and/or restrict the field view. During day, detecting the beacons is hard. Badge 200 would have to be very close to the emitter before it can detect them. To counter this, the controllers of beacons 320 and 330 increase, the amount of emitted infrared light and/or enlarge the field view.

The relationship between the light level and the beacon settings may be determined during/after manufacturing or later after the beacon has been installed. For a range of different light level conditions, the beacon behavior parameter, e.g., the diameter of the field of view, may be determined (possibly using multiple measurements). These results are stored, e.g., as a list of pairs (possibly sub-sampled), or as a mathematical equation(s), etc. The relationship, equations, list of pairs etc, may be stored in memory 140.

Figure 5 illustrates as a schematic block diagram a configuration system 500. System 500 comprises an infrared detector 510, A first interface 520 for receiving an indication from a user, A second interface 530 with a controller of an infrared beacon and a memory 540. The system may be embodied in a single configuration device. However, the system may also be distributed; for example, the infrared detector 510 may be a badge 200. The first and second interfaces 520, 530 may be a mobile phone application. Memory 540 may be in a server, communicating with the mobile phone application. Memory 540 may be memory 140. Memory 540 may be in beacon 100.

Figure 6 illustrates a room 600 during configuration of beacon 620 with configuration system 500. The room contains one or more infrared beacons, shown are two beacons: infrared beacon 620 and infrared beacon 630. Figure 6 shows multiple locations 631- 634 at which the mobile infrared detector is placed (with or without the rest of the configuration system). Furthermore, a desired field of view 640 is indicated by a dotted line. A desired field of view means that the localization system should operate after configuration such that a badge 200 inside view 640 detects beacon 620 but outside view 640 would not detect beacon 620, regardless of ambient lighting conditions.

During operation mobile infrared detector 510 is placed at a location in room 600, say at location 631. Through first interface 520 the user indicates whether this location is or is not within the desired field of view. For example, the user may be offered a choice between 'Visible or Invisible?', e.g., via a display of system 500. The user may respond, via an input device, say a touch pad, if the beacon should be visible from this position or not. For location 631 and 632, the user would select visible. For locations 633 and 634 the user would select invisible. Through the second interface the controller of beacon 100 is instructed to regulate infrared visibility of the infrared beacon to at least two different states. For example, the level of light emitted may be changed and/or a setting of the field of view mechanism may be changed.

For each state the infrared visibility of the infrared beacon from the current location of the infrared detector is determined. The desired visible/invisible indication is stored in memory 540 together with the amount of ambient light obtained, e.g., from detector 120, e.g., through the second interface and an indication whether the infrared emitter visible from the current location of the infrared detector for each of the states. Next the detector 510 is moved to a new location, and the process is repeated. The process is also repeated with different levels of ambient light.

A relationship between multiple amounts of ambient light and associated settings of the infrared beacon is thus obtained and stored in a memory. Memory 540 may be used as a temporary memory, before it is transferred to memory 140. Controller 130 uses memory 140 to retrieve the relationship.

The light level beacon relations may be stored as pairs, i.e. a list of <light level, beacon parameter pairs. The beacon parameter can be e.g., the diameter of the field of view, the best beacon power, the best lens/cone setting or other parameters describing beacon behavior or the field of view. Alternatively, the light level beacon relation may also be stored as one or multiple mathematical equations.

After the system is installed, a person uses this device, e.g., system 500, to measure the amount of IR light at some locations which should be within the field of view of the beacon, and at some locations that should be beyond the field of view of the beacon. He does so by physically moving to a location and choosing one of two control options ("location in field of view'V'location outside field of view") to start the measurement cycle. In a measurement cycle, the IR and visible light levels are measured at the same time and the system determines the IR visibility for a range of beacon settings in real-time. The resulting range of visible light intensities, IR light intensities, and corresponding beacon settings are stored along with whether they should be within the field of view. After completing the cycle, the user is informed about this, and he may move towards another physical location and start the cycle again. By applying this method at different moments with different visible lighting conditions, the light- level beacon relations can be defined, either gradually over time, or in one go by manipulating the visible lighting conditions, e.g., using curtains or blinds.

Based on the measured visible light conditions, the IR measurements, the beacon settings and whether the IR should or should not be visible, it is possible to determine the required beacon setting(s) for each location. The collection of settings for all locations can be used to find the best setting to satisfy all requirements, or a setting that violates the least number of requirements. Alternatively, pattern recognition/data mining methods can be used to automatically learn the relationships between beacon settings and proper visibility of the IR field using the stored data. For example, classification methods such as SVM, neural nets, and decision trees can be used.

The learned relationships can also be updated every now and then by executing new measurements, and possibly removing data that is considered being too old.

For example, a result of using the configuration system may be the following data: Visible light level 1 , IR level 1 , beacon setting 1 , visible

Visible light level 2, IR level 2, beacon setting 2, visible

Visible light level A, IR level A, beacon setting A, invisible

Visible light level B, IR level B, beacon setting B, invisible

The data may be processed by a system for constructing light level beacon relations to obtain a more easily used list: Visible light level 1 , beacon setting 1 ,

Visible light level 2, beacon setting 2.

The latter list may be stored in memory 140.

Figure 7 shows a flowchart 700 illustrating a method of controlling an infrared beacon. In step 710 the amount of ambient light outside the infrared beacon is measured. For example, a voltage is measured of a visible light detector arranged at the outside of an infrared beacon. The measured voltage may be used as a representation of the amount of ambient light. In step 720 a setting for the infrared visibility is obtained corresponding to the measurement of a visible light detector. The infrared visibility is configured to a high level if ambient light levels are high and configured to a low level is ambient light levels are low. For example, a formula is retrieved from memory 140 and evaluated, by controller 130, for the amount of ambient light, the formula giving the corresponding infrared visibility; for example the corresponding infrared visibility is obtained from a look-up table in which the amount of ambient light is found. The look-up table may also be used to find the closest value; or to find the closest two and interpolate. In step 730 the infrared visibility of the infrared emitter is regulated in accordance with said corresponding setting.

Figure 8 shows a flowchart 705 illustrating a method of configuring an infrared beacon. In step 740 a mobile infrared detector is moved to a new location. The infrared detector may also be mobile because it is comprised in a mobile configuration device or in a badge, etc. In step 750 an indication is received from a user indicating if the current location of a mobile infrared detector is inside or outside a desired field of view. For example, the user may touch an area of a touch display indicating visibility, i.e., inside the desired field of view, or touch an area of a touch display indicating invisibility, i.e., outside the desired field of view. In step 760 the infrared visibility of the infrared beacon is regulated to a new state; e.g., the field of view mechanism is moved in a new position, or the emitter is increased or decreased in brightness. In step 770 the infrared visibility of infrared beacon is determined from the current location of the infrared detector. Step 760 and 770 are done multiple times; they are repeated at least once. Preferably steps 760 and 770 are executed more often, say, 4, or 8, or even more times. The combinations of state of the infrared beacon, i.e., setting of emitter and setting of field of view mechanism, and measured infrared visibility are stored together with the indication and the amount of ambient light. Storing is done in step 780. Next the entire process, starting at step 740 is repeated for a different location of the detector. Preferably, locations in and outside the desired field of view are used. Next flowchart 705 may be repeated for different levels of ambient light.

The results of this process may be processed further. For each level of ambient light, a state is selected for which the desired visibility best conforms to the measured visibility. For example, the most matches may be used, or sum of squared errors. In this way not all measure results need to be kept, although this is possible.

Many different ways of executing the method are possible, as will be apparent to a person skilled in the art. For example, the order of the steps can be varied or some steps may be executed in parallel. Moreover, in between steps other method steps may be inserted. The inserted steps may represent refinements of the method such as described herein, or may be unrelated to the method. For example, steps 760 to 780 may be executed, at least partially, in parallel. Moreover, a given step may not have finished completely before a next step is started.

A method according to the invention may be executed using software, which comprises instructions for causing a processor system to perform method 700 and 705. Software may only include those steps taken by a particular sub-entity of the system. The software may be stored in a suitable storage medium, such as a hard disk, a floppy, a memory etc. The software may be sent as a signal along a wire, or wireless, or using a data network, e.g., the Internet. The software may be made available for download and/or for remote usage on a server.

It will be appreciated that the invention also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source code, object code, a code intermediate source and object code such as partially compiled form, or in any other form suitable for use in the implementation of the method according to the invention. An embodiment relating to a computer program product comprises computer executable instructions corresponding to each of the processing steps of at least one of the methods set forth. These instructions may be subdivided into subroutines and/or be stored in one or more files that may be linked statically or dynamically. Another embodiment relating to a computer program product comprises computer executable instructions corresponding to each of the means of at least one of the systems and/or products set forth.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. An infrared beacon (100) comprising

an infrared emitter (1 10) for emitting infrared light

a light sensor (120) for measuring the amount of ambient light outside the infrared beacon, and

a controller (130) for regulating the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon the measured amount of ambient light.

2. An infrared beacon as in Claim 1 , wherein the controller is configured to increase infrared visibility if the measured amount of ambient light increases over a first level, and wherein controller is configured to decrease the infrared visibility if the measured amount of ambient light decreases below a second level.

3. An infrared beacon as in any one of the preceding claims, wherein the controller is configured to regulate the amount of infrared light emitted by the infrared emitter to regulate the infrared visibility.

4. An infrared beacon as in Claim 3, wherein the controller regulates a voltage across the infrared emitter between a low voltage value and a high voltage value.

5. An infrared beacon as in any one of the preceding claims, comprising a field of view mechanism (150) controlling the field of view from the infrared emitter towards the outside of the infrared beacon, and wherein the controller is configured to regulate the field of view mechanism to regulate the infrared visibility.

6. An infrared beacon as in Claim 5, wherein the controller is configured to increase infrared visibility by enlarging the field of view using the field of view mechanism and wherein the controller is configured to decrease infrared visibility by reducing the field of view using the field of view mechanism.

7. An infrared beacon as in Claim 5 or 6 wherein the field of view mechanism comprises any one of: a cone having a controllable base and arranged with the infrared emitter at the apex of the cone; a lens; a controllable aperture.

8. An infrared beacon as in any one of the preceding claims comprising a memory, the memory storing a relationship between multiple amounts of ambient light and associated settings of the infrared beacon, the controller is configured to obtain a setting of the infrared beacon associated with the measured amount of ambient light from the memory and to regulate the infrared visibility of the infrared emitter from outside the infrared beacon in accordance with said setting of the infrared beacon.

9. An infrared beacon as in Claim 8, wherein the memory comprises a list of multiple pairs of a amount of ambient light and an associated setting of the infrared beacon, and wherein the controller is configured to retrieve a stored amount of ambient light closest to the measured amount of ambient light and to regulate the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon said setting of the infrared beacon.

10. A localization system comprising a beacon as in any of the preceding claims and a locator device, wherein

the infrared beacon is configured to encode a digital beacon identifier in the emitted infrared light, and

the locator device comprising

an infrared detector for detecting the emitted infrared light and obtaining the beacon identifier from the detected emitted infrared light, and

a transmitter for transmitting the beacon identifier and a user identifier.

1 1. A configuration system for configuring an infrared beacon, comprising

a mobile infrared detector, for determining the infrared visibility of infrared beacon from a current location of the infrared detector,

a first interface for receiving an indication from a user indicating if the current location of the infrared detector is inside or outside a desired field of view,

a second interface with a controller of the infrared beacon for regulating the infrared visibility of the infrared beacon to at least two different states, and

a memory for storing the indication and the infrared visibility of the infrared emitter from the current location of the infrared detector as determined by the infrared detector for each of the at least two different states.

12. A method of controlling an infrared beacon comprising an infrared emitter, the method comprising

measuring the amount of ambient light outside the infrared beacon,

regulating the infrared visibility of the infrared emitter from outside the infrared beacon in dependence upon the measured amount of ambient light.

13. A method of configuring an infrared beacon, comprising

receiving an indication from a user indicating if the current location of a mobile infrared detector is inside or outside a desired field of view,

regulating the infrared visibility of the infrared beacon to at least two different states, determining the infrared visibility of infrared beacon from a current location of the infrared detector for each of the at least two different states, storing the indication and the infrared visibility of the infrared emitter from the current location of the infrared detector for each of the at least two different states.

14. A method as in Claim 13, further comprising

moving the mobile infrared detector to at least a location inside the desired field of view and to a location outside the desired field of view.

15. A computer program comprising computer program code means adapted to perform all the steps of any one of claims 1 1-14 when the computer program is run on a computer.

16. A computer program as claimed in claim 15 embodied on a computer readable medium.